Comparison of the ribose-complexes of T. maritima and E. coli RBPs. Close-up view of polar amino acids (gray) in tmRBP (A) and ecRBP (PDB code 2DRI) (B) that form a hydrogen-bonding network (black lines) with ribose (green). (C) Close-up view of the aromatic binding pocket residues of ecRBP (cyan) and tmRBP (blue). Phenylalanine (F15) in ecRBP is replaced by tryptophan (W15) in tmRBP. Superposition of the two structures reveals that the six-membered ring of the tmRBP tryptophan indole is coincident with the ecRBP phenylalanine six-membered ring.